Sore throat, or pharyngitis, is the result of inflammation with pain of the throat (especially on swallowing), perceived dryness and congestion of the mucous membrane. Sore throat is a common complaint in the upper respiratory tract and can range from mild irritation to incapacitating pain.
Oral sore throat preparations, such as lozenges, sprays, solutions and the like, containing topical anesthetic/analgesic agents have long been used for the symptomatic relief of sore throat. Dyclonine HCl, a member of a class of compounds known as .beta.-aminopropiophenones and which is chemically denoted as 3-piperidino-4'-butoxypropiophenone hydrochloride, is a well known anesthetic/analgesic agent for topical use on the mucous membranes of the mouth and throat (see Federal Register, Vol. 47, No. 101, Proposed Rules, pages 22810-13, 1982). Oral pharmaceutical compositions of dyclonine HCl commercially available in the United States include an aqueous liquid spray containing 0.1% dyclonine HCl and solid lozenges containing 1.2 mg per lozenge for children and 3.0 mg per lozenge for adults (see Physicians' Desk Reference for Non-prescription Drugs, 8th Ed., 1987, pages 518-9). The benefit of dyclonine HCl is that it provides long-acting topical anesthetic relief. The use of certain acids, particularly citric acid, to stabilize dyclonine HCl in anesthetic lozenges is reported in U.S. Pat. No. 4,139,627 to Lane et al., issued Feb. 13, 1979. In addition to its anesthetic/analgesic properties, dyclonine HCl is reported to possess antimicrobial activity. In this regard, U.S. Pat. No. 2,868,689 to Florestane et al., issued Jan. 13, 1959 discloses stabilized aqueous preparations of dyclonine HCl (0.1-5%) having topical anesthetic and antimicrobial action, the stabilization aspect being provided by the addition of chlorobutanol (0.1-0.5%).
U.S. Pat. No. 2,928,767 to Gulesich et al., issued Mar. 15, 1960 teaches the stabilization of phenothiazines (compounds totally unrelated to .beta.-aminopropiophenones), which are subject to light-catalyzed decomposition by use of saccharin or preferably, a saccharin salt. It has now surprisingly been found that saccharin is a very satisfactory stabilizer for .beta.-aminopropiophenones, particularly dyclonine.
It is therefore an object of the present invention to provide oral anesthetic pharmaceutical compositions comprising .beta.-aminopropiophenones. It is a further object of the present invention to provide dyclonine-containing oral anesthetic pharmaceutical compositions which provide improved stability. It is still a further object of the present invention to provide a method of using these anesthetic pharmaceutical compositions to treat humans or animals in need of such treatment. It is still a further object of the present invention to provide a novel process for the manufacture of anesthetic lozenges.